Method of and apparatus for atuomatically clearing a directive gun from obstacle

ABSTRACT

A method of clearing a biaxially directive gun from obstacles lying at a fixed position in relation to the gun position. The method is used in conjunction with guns which are positioned by a gunner operated sight via a selsyn. The normal control signals transmitted from the gunner operated sight to the gun director circuits are interrupted at predetermined azimuth and elevation positions corresponding to an obstacle location, and preset azimuth and elevation signals are interposed to avoid the obstacle. An example of logic circuitry and other apparatus for implementing the method of the invention is disclosed.

hinted States Patent 1191 1111 3,731,589

Pfeiffer et al. 1 May 8, 1973 54 METHOD OF AND APPARATUS FOR 2,434,654 1/1948 Watkins et a1 ..89/134 UX ATUQMATICALLY CLEARING A 5 2,628,535 2 1953 Terwilligeretal. ..89/4l.2

DIRECTIVE GUN FROM OBSTACLE Inventors: Rolf D. Pfeiffer; Wolf l). Gruenberg,

both-of Doernigheim, Germany Honeywell G.m.b.H., Frankfurt am Main, Germany Filed: Apr. 3, 1969 Appl. No.: 814,890

Assignee:

US. Cl. ..89/41 C, 318/626 Int. Cl. ..F41g 5/14 Field Of Search ..89/4l R, 41 C, 41 ME, 89/139, 135; 318/626, 627

References Cited UNITED STATES PATENTS 5/1934 Mittag et al ..89/4l.2 UX

Primary Examiner-Stephen C. Bentley Attorney-Charles J. Ungemach, Ronald T. Reiling and Albin Medved [57] ABSTRACT and preset azimuth and elevation signals are inter-- posed to avoid the obstacle. An example of logic circuitry and other apparatus for implementing the method of the invention is disclosed.

9 Claims, 17 Drawing Figures 1 0 1 'lll'illllff'l'l'ln PATENTEUHAY' a ma SHEET 1 [IF 5 Nu m I MOE INVENTORS WOLF D. GRUENBERG ROLF D.

PFEIFFER ATTORNEY PATENTED 8W5 3.731.589

sum 2 OF 5 INVENTORS WOLF D. GRUENBERG ROLF D. PFEIFFER ATTORNEY PATENTE MAY 81973 SHEET 3 OF 5 N UK N on 5 5m wm OAOImmmIF INVENTORS ATTORNEY WOLF 0. GRUENBERG ROLF 0. PFEIFFER PATENTED 3.731.589

SHEET u 0F 5 INVENTORS WOLF o. GRUENBERG ROLF o. PFEIFFER BY M; M

ATTORNEY Jut PATENTEW 8% 3,731,589

SHEET 5 0F 5 RELAY RELAY FIG. I?

RELAY FIG I6 1N VENTORS WOLF D. GRUENBERG ATTORNEY MPFEIFFER Y METHOD OF AND APPARATUS FOR ATUOMATICALLY CLEARING A DIRECTIVE GUN FROM OBSTACLE I BACKGROUND OF THE INVENTION 1 Field of the Invention The present invention pertains to the field of geometrical instruments and, more particularly, to ordnance gun sights of the light-ray type.

2. Description of the Prior Art Prior art gun directioning devices have commonly used firing interlocks to prevent actuation of a gun whenpositioned at a particular angle to prevent firing at obstacles located within the field of positioning. The problem becomes particularly acute with naval guns and guns positioned on armored vehicles where it is important that the gun itself should not hit any superstructure, observation cupolas, searchlights, etc. In directly positioned weapons, it is well-known to prevent positioning of the gun to particular sectors or positions by the use of cams or blocking linkages within the gun drive.

The present invention provides for the automatic clearance of obstacles by guns which are not positioned, directly by the gunner but are slaved to a gunner operated sight via a selsyn circuit.

It is an object of the present invention to provide a method for automatically avoiding obstacles within the path of a bi-axially directionable gun.

It is a further object of the present invention to provide a method for utilizing the maximum field of traverse of the gun by sensing deflection rates to allow use of the gun in close proximity to an obstacle.

It is a further object of the present invention to provide improved apparatus for the automatic clearance of a bi-axially directionable gun from obstacles.

SUMMARY OF THE INVENTION The method of the present invention operates by interrupting the control signals between a gunner operated sight and the gun drive circuit. Predetermined positions of azimuth and elevation are sensed and applied as inputs to logic circuitry along with the directioning signals from the gunner operated sight to cause signals to be applied tothe gun drive circuitry controlling the gun to avoid obstacles within the path of azimuth rotation. The invention provides for automatic rate sensing to modify the clearance path and allow greater use of the available gun positions.

The method of the invention also provides for sensing positions in close proximity to an obstacle to cause the gun to be backed away from the obstacle before an avoidance path is begun.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 3 is a linear representation of a rotary contactor having switch segments corresponding to proximity zones positioned at the points of abrupt changes in elevation.

FIG. 4 is a linear representation of a rotary contactor for sensing the elevation position of the gun, with segments corresponding to the elevations of the obstacle.

FIG. 5 represents a typical control circuit linking the selsyn drive of the gunner operated sight with the vertical positioning circuitry of the gun drive including apparatus for implementation of the method of the present invention for avoiding an obstacle of three different heights.

FIG. 6 shows the control circuitry between the gunner operated sight and the azimuth drive circuitry for the gun including apparatus for reversing the azimuth drive signal in accordance with the method of the present invention.

FIG. 7 is a surface view of a rotary contactor corresponding to the linear representation in FIG. 2 of azimuth positions.

FIG. 8 is a surface view of a rotary contactor corresponding to the linear representation in FIG. 3 of the azimuth proximity zones.

FIG. 9 is a surface view of a rotary contactor of an alternate embodiment to the contactor shown in FIG. 7 wherein all switch segments are on one surface of the contactor.

FIG. 10 is a surface view of a rotary contactor corresponding to the linear representation of elevation shown in FIG. 4.

FIG. 11 represents control circuitry for sensing the azimuth rate signal to actuate the gun drive circuitry for avoiding the obstacle.

FIG. 12 shows circuitry for sensing the approach of the gun to an obstacle and for actuating the circuitry of FIG. 11.

FIG. 13 represents the logic circuitry for implementing the method of the invention for avoiding the first section of the obstacle.

FIG. 14 shows logic circuitry according to the. method of the present invention for elevating the gun above the center region of the obstacle.

FIG. 15 shows logic circuitry for implementing the method of the invention in elevating the gun above the third section of the obstacle.

FIG. 16 of the invention shows logic circuitry to implement a reversal of the azimuth drive during a righthand azimuth swing when the gun position lies within one of the proximity zones illustrated in FIG. 3.

FIG. 17 shows logic circuitry for implementing azimuth drive reversal during a left-hand .turn when the gun position lies in one of the proximity zones shown in FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 2 is a linear representation of a circular contactor Cl having a first side subdivided into four segments S2, S4, S6, and S8. These segments correspond to areas of varying elevation required due to obstacles, in the 360 azimuth of the gun. It will be noted that the region designated S8 is continuous and that no obstacle exists in this range of azimuth positions. The opposite side of the contactor C1 contains four contacting segments positioned slightly ahead of any impending increase in elevation. The first and second sides of the disk are contacted by wipers Al and A2, respectively. Wipers A1 and A2 are adjusted by the azimuth drive in synchronization with the gun and are connected to a voltage source providing a suitable logic level signal which will be dependent upon the nature of the logic circuitry chosen for implementation of the invention. Output leads are connected to each of the segments S1 through S8, energized in accordance with the azimuth position of the gun from the signals applied to the wipers A1 and A2.

Similarly, in FIG. 3, a circular contactor C2 is provided with conducting segments Pl through P4 and a contacting wiper A3. The position of the segments P1 through P4 is such that the segments will be energized by the wiper A3 whenever the gun is in proximate relation to the abrupt changes in elevation of the desired obstacle pattern. These zones thus serve as proximity zones. Output leads are connected to each of the proximity zone segments P1 through P4. Thus, the output lines are energized from the signal applied to wiper A3 in accordance with the azimuth position of the gun.

Referring to FIG. 4, showing a contactor C3, one side of the contactor is divided into six segments, designated EO through E5. A wiper arm E driven in synchronization with the elevation drive of the gun applies a control signal to one of the segments in accordance with the elevation position of the gun. It will be noted that segments E through E4 comprise a90 elevation range with a 15 depression below the horizontal possible. The region beyond the 90 range, designated E5, is not of interest-as the gun will not be positioned in this range.

FIGS. 7, 8 and 10 represent surface views of the contactors C1, C2 and C3 respectively. In FIG. 7, the first side of the contactor is shown with segments S2, S4, S6 and S8 appearing in solid outline. On the reverse side, the segments S1, S3, S and S7 are located, outlined in dashed lines.

FIGS. 8 and 10 represent the contactors C2 and C3, respectively. It will be noted that inFIG. 10 the disk may be segmented in different ways, depending on the drive ratio between the wiper E and the elevation drive of the gun. Thus, it would not be necessary to utilize the full 360 disk.

FIG. 9 represents an alternate embodiment of FIG. 7 where all segments appear on the same surface of the contact disk.

In FIG. 5, the interconnection link between the selsyn drive located at the gunner operated sight and the elevation logic circuit EL is shown. The elevation logic EL is connected to the elevation drive ED of the above the obstacle independent of the signals present on the gun drive input lines. The elevation signals corresponding to the three different levels of the obstacle pattern are generated in the elevation signal generator ESG. Activation of relays K1, K2 and K3 is in accordance with logic circuitry yet to be described.

FIG. 6 shows the azimuth control lines connected from the selsyn drive to the azimuth logic circuitry AC which in turn is connected to the azimuthdrive AD. The azimuth control signals from the sight consist of a right signal, AR, and a left signal AL. The azimuth lines are connected to the azimuth logic AC through a pair of normally closed relay contacts. Also connected to the azimuth inputs of the azimuth logic circuit is an azimuth signal generator ASG which is applied to the azimuth input at the time relay K5 or K6 is energized which simultaneously opens the line from the sight selsyn. The energization of the relays K5 and K6 is in accordance with logic circuitry connected with the proximity segments which is to be described.

Actuation of either relay K5 or K6 thus interrupts the I drive signals AL or AR, respectively, present on the gun. The elevation signals from the sight comprise a a three parallel relay contacts are three elevation signals corresponding to the three different elevations of the obstacle. Depending upon which relay is energized, one of these signals is applied to the elevation increase input of the elevation logic circuit to raise the gun input lines to the azimuth logic AC which simultaneously applies a signal for azimuth control generated in the azimuth signal generator ASG. The polarity of the signal applied to the azimuth logic circuit input is in opposition to the normal signal applied on that line; that is, a positive signal is applied from the azimuth signal generator to the azimuth right AR input which normally carries a negative signal upon an order from the gun sight to change azimuth in a right-hand direction. The same holds true for the azimuth left input AL to the logic circuitry.

FIG. 11 shows a circuit for changing the avoidance path which the gun takes in avoiding the obstacle dependent upon the azimuth rate of rotation.

A positive signal dependent upon the rate of rotation is applied to-an input terminal 11 which is connected through the normally-open contacts of a single pole double throw relay K4-1 to junction 12. Junction 12 is connected through the normally-closed contacts to a point of reference potential 13. Junction point 12 is connected to the input terminal 14'of an operational amplifier 16 through a resistor 15. Connected in parallel with resistor 15 between terminals 14 and I2 is a resistor 17 in series with a diode 18 with the direction of current flow toward the input of operational amplifier 16. At the junction between resistors 17 and 18 a resistor 19 is connected between the junction and a source of negative reference potential 20. A resistor 21, connected in series with a diode 22 is also connected between terminals 12 and 14. The direction of current flow is again toward the input of the operational amplifier 16. A resistor 23 is connected between the junction of resistor 21 and diode 22 and a source of negative reference potential 24.

The operational amplifier 16 has an output terminal 25. The output terminal 25 is connected through a normally-closed relay contact K4-2 to the input 14 of the operational amplifier 16. Connected in parallel with the normally-closed contact in the feedback loop is a capacitor 26.

A normally-open threshold switching circuit 27 is connected between the output temiinal 25 and input terminal 28 of logic circuitry generally referred to as 29. The logic circuitry 29, yet to be described, is connected to the gun drive GD. Also applied to the input of the logic circuitry 29 is the azimuth control signal at input and, at input 31, a signal from the elevation contactor disk C3. The makeup of logic circuitry 29 will be explained with reference to FIGS. 13-15.

Relay K4 is actuated by a turn-on condition of an NPN transistor 38 in FIG. 12. The coil 39 of relay K4 is connected in series with a source of positive voltage connected to terminal and the collector of transistor 38. The emitter of transistor 38 is connected to a point of reference potential. The base of transistor 38 is connected via lead 37 to the output of a three input OR cir-, cuit 33. The three inputs of the OR circuit 33 are 34, designated X, 35, designated Y, and 36, designated 2.

The inputs X, Y, Z are dependent on azimuth position as indicated by contactor C1. The purpose of the circuit shown in FIG. 11 is to establish an avoidance path of the gun to avoid an obstacle which it is approaching. Consequently, the inputs to the OR circuit 33 are connected to various points in the logic circuitry to be described for indication of the approaching obstacle. A signal entering anyone of the input lines thus actuates the relay K4 which opens the feedback loop for operational amplifier 16 in FIG. 11 and applies the azimuth rate signal to the junction 12 in FIG. 11. Between junction 12 and input 14 to operational amplifier 16, a variable resistance input network is provided with the effective input resistance dependent on the rate signal present at junction 12. It will be noted that the diode 18 is reverse biased depending on the voltage level at terminal 20 and resistors 17 and 19. Similarly, diode 22 is reverse biased dependent on the voltage level at terminal 24 and the resistors 21 and 23.

If the input signal at terminal 12 is of a predetermined magnitude, both diodes 18 and 22 will become forward biased and resistors l5, l7, and 21 will be placed in parallel, thus reducing the effective input impedance to operational amplifier 16. For a signal at junction 12 of lesser magnitude, only one of the diodes will become forward biased with a resultant higher input impedance. Similarly, for a small signal at junction 12, neither diode 18 nor diode 22 will become forward biased and the total input impedance will be that of resistor 15. Thus, with a rapid azimuth rate, integration in the operational amplifier circuit with capacitor 26 operates with a much smaller time constant due to the reduced input impedance. With a small signal, the time constant is resultingly higher. This corresponds to the need for a more rapid deviation in a vertical direction for higher azimuth rates.

The output of the integrator circuit at terminal 25 is applied to a threshold switch 27. The threshold switch provides an output S at input 28 to logic circuitry 29 whenever the signal at terminal 25 at the output of the integrator exceeds a predetermined level. As the magnitude of the voltage at the input terminal 11 is a function of the rate and the signal at terminal 25 applied to the input of the threshold switch is an integration of this level, the threshold value, actuating the threshold switch 27 connecting terminal 25 to the input 28 of logic circuitry 2? will occur earlier with a high rate of azimuth rotation than with a low rate of rotation. Because it is desirable to compensate for the higher rate by a more rapid onset of deflection as well as causing the deflection to start at a greater distance from the obstacle dependent on the rate, the variable impedance input circuitry previously described is included. With suitable selection of the values for the variable impedance input circuitry, the signal appearing at terminal 25 becomes to a good approximation a square function of the input voltage at terminal 12. Thus the onset point is shifted toward the beginning of the deflection zone and a safe clearance of the obstacle is guaranteed. (The signal at terminal 14 will be a function of the signal at terminal 11 with the variable impedance input network. The integral of this function provides a squared function at the output of the integrator at terminal 25).

FIG. 13 is a representation of logic circuitry suitable for accomplishing the method of the present invention for avoiding a first level of the obstacle, represented on the vertical elevation disk as the segment El.

Segments S5 and S6 of rotary contactor C1 shown in FIG. 7 are connected to the two inputs of an OR gate 40. The output of OR gate 40 is connected to one of two inputs of an AND gate 41; the other input is connected to segment E1 of the vertical elevation contactor C3 shown in FIG. 10. The output of AND gate 41 is connected to one input 48 of an OR gate 45. Segments E0 and E1 of elevation rotary contactors C3 are connected to the two inputs of an OR gate 42. The output of OR gate 42 is connected to one of three inputs of an AND circuit 43. One of the other three inputs of the AND gate 43 is connected to segment S7 of contactor C 1 while the other input to the gate is connected to the left azimuth control line AL from the gun sight. The output of AND gate 43 is connected to input 34 of OR gate 33 shown in FIG. 12 which is the X input. The output of AND gate 43 is also connected to one input of an AND gate 44. The other input to AND gate 44 is connected via lead 28 to the output of the threshold switch 27 shown in FIG. 11. The output of AND gate 44 is connected to input 49 of the OR gate 45. Also connected to OR gate 45 at input 47 is a signal V The output of OR circuit 45 provides a signal V, and is connected to the base of an NPN transistor 51. The emitter of NPN transistor 51 is connected to a point of reference potential. A relay coil K1 is connected between a positive voltage terminal 52 and the collector of NPN transistor 51.

Operation of FIG. 13 will be described in relation to a desired gun movement from point B to point A shown in FIG. 1. With the gun at point B, the elevation contactor is in region E0. As the gun moves toward the left it is necessary to elevate the gun to the height H1 upon entering deflection sector S7. As relay- Kl must be activated to insert a vertical drive signal to the gun logic circuitry in FIG. 5 to avoid the obstacle of height H1, the transistor 51 in FIG. 13 must be turned on to activate the coil of relay K1. For the gun positioned in either sectors E0 or E1, an output will appear at the OR gate 42. At the AND gate 43, a signal on S7 and a left azimuth control signal together with the output from OR gate 42 will activate the AND gate 43. The output of AND gate 43, connected to input 34 of OR gate 33 in FIG. 12, causes relay K4 to be activated which in turn connects the azimuth rate output to the circuitry in FIG. 1 1, previously described. The signal is also supplied to one input of AND gate 44. At the time the threshold point is reached and an output appears at the output of threshold switch 27 in FIG. 11, the AND gate 44 will be activated and applied to one of the inputs of the OR gate 45 which in turn is activated causing relay Kl to pull in through turn-on of transistor 51.

When operating in the azimuth region represented by segment $6 a signal is present at either one or both of the inputs of OR circuit 40. An output at the OR circuit 40 activates the AND gate 41 whenever a signal is present on segment E1. This activates OR gate 45 which activates relay Kl to elevate the gun above the level I-Il. This part of the circuitry assures that the gun necessary avoidance drive signal from the B80 in FIG.

' 5. The two AND circuits 54 and 55 are applied to the from either direction and thus contacts S3 and S with will never lie in the region of the obstacle denoted by I segment S6 and segment E1 even in the absence of any azimuth rate signal and hence a signal on the S input to AND gate 44. This would occur in situations where the gun was to be lowered into the regions S6 without any azimuth variation.

FIG. 14 shows the logic circuitry which may be used to implement the method of the present invention for avoiding the central portion of an obstacle as used in the example and shown in FIG. 1. This region of the obstacle is outlined by segments S4 and vertical segments El plus E2 plus E3.

The two-input AND circuit 54 has its two inputs connected to the azimuth right control line AR and segment S3 of the azimuth rotary contactor C1. The output of AND circuit 54 is connected to one of two inputs of OR circuit 58. The other input of OR circuit 58 is connected to the output of an AND circuit 55 having as inputs the azimuth left control line AL and a lead connected to segment S5 of the azimuth contactor C1. The output of OR circuit 58 is connected to input 59 of AND circuit 64. Input 60 of AND circuit 64 is connected to the output of OR circuit 63. OR circuit 63 has its two inputs connected to the vertical contactor segments E2 and E3.

The output of AND circuit 64 is connected to input terminal 36 of OR circuit 33 in FIG. 12, designated Z. The output of AND circuit 64 is also connected to input 65 of AND circuit 67. Input 66 of AND circuit 67 is connected to the output of the azimuth rate logic circuit to receive the signal S. The output of AND circuit 67 is connected to input 70 of OR circuit 68. Input 69 of OR circuit 68 is connected to V the output of a comparator circuit to be described. Input 71 to OR circuit 68 is connected to the output of an AND circuit 72 having two inputs connected to segment S4 of the azimuth contactor C1 and segment E3 of the vertical elevation contactor C3. The output of OR circuit 68 is connected to the input of the comparator circuit through lead 75 and to the base of an NPN transistor 76. The emitter of NPN transistor 76 is connected to a point of reference potential. The collector of NPN transistor 76 is connected to one end of a relay coil K3 which is connected between the collector and a point of positive voltage 77.

In operation, the portion of the obstacle indicated by segments S4 and E3 on the azimuth and elevation contactors respectively is prohibited to the gun movement through AND circuit 72. When signals are present on both input lines to AND circuit 72, the OR circuit 68 will activate the transistor 76 which in turn causes relay K3 to be pulled in, opening the control line to the input of the elevation logic E1 in FIG. 5 and applying a the azimuth signal right or left respectively. The OR circuit 63 is activated whenever the gun lies in a vertical position between height H1 and H3. Activation of the azimuth rate logic circuitry through the signal Z causes an eventual signal S at input 66 of AND circuit 67. The signal S will depend upon the azimuth rate as determined by the azimuth rate logic circuitry. The output to the AND circuit 67 is connected to input of OR circuit 68 to activate the relay K3 whenever approaching the central portion of the obstacle from either direction.

Referring to FIG. 15, showing the logic circuitry for activation of relay K2 for avoidance of the obstacle region denoted by region S2 and height E1 plus E2, a three-input OR circuit 80 has its inputs connected to the vertical elevation segments E0, E1, and E2 of elevation contactor C3. The output of OR circuit 80 is connected to one of the inputs of the three-input AND circuit 81. The other two inputs of the AND circuit 81 are connected to segment S1 of the azimuth contactor C1 and the azimuth right drive signal AR. The output of AND circuit 81 is connected to one of the two inputs of AND circuit 83. The output of AND circuit 81 is also connected by a line 82 to input 35 of OR circuit 33, designated Y, in FIG. 12. The other input to AND circuit 83, designated 84, is connected to receive the output signal S of the azimuth rate logic circuitry of FIG. 11.

Segments S2 and S3 are connected to the two inputs of an OR circuit 89, the output of which is connected to one of two inputs of AND circuit 90. The other input of AND circuit 9%) is connected to elevation segment E2. The output of AND circuit 90 is connected to input 88 of OR circuit 85. Input 86 to OR circuit is connected to the output V,, of the comparator circuit to be described. The other input 87 to OR circuit 85 is connected to the output of AND circuit 83. The output of OR circuit 85 is connected to the base of NPN transistor 92. The output of OR circuit 85 is also connected through lead 91 to the input V of the comparator circuit. The emitter of NPN transistor 92 is connected to a point of reference potential. A relay coil K2 is connected between a point of positive potential 93 and the collector of NPN transistor 92.

In the operation of the circuitry shown in FIG. 15, the region of height H2 is excluded from possible gun positions by the OR circuit 89 which is activated when the azimuth lies within the region S2. The AND circuit is then actuated to in turn activate the relay K2 whenever the elevation lies in the region E2. In approaching the section from the left, an azimuth right signal exists on the input to the AND circuit 81. As soon as the azimuth reaches region S1 and the elevation is anywhere in the regions indicating a height less than H2, the AND circuit 81 will be activated which in turn actuates the azimuth rate logic circuitry and eventually produces a signal S at the input to the AND circuit 83. The azimuth rate logic output S dictates when the relay K2 will be activated to avoid the obstacle and is dependent on the azimuth rate of the gun.

The operation of a comparator circuit connected between V and V shown in FIGS. 13 through will now be explained. As the elevation is increased and the region which it is desired to avoid is passed, the OR gates will become nonconductive and the elevation relay will drop out. In the example where the gun is moved from point A to point B in FIG. 1, at any point in the elevation, the signal from the gun control will still be an elevation decrease signal. This would cause the gun to oscillate about the horizontal border lines of the different levels of the obstacle. This oscillation is undesirable and a comparator circuit, not shown, is switched on by the signal V whenever any one of the relays is actuated. After actuation by the signal V,, the comparator circuit compares the magnitude of the control handle signal with the signal commanded by the automatic deflection apparatus.

When the control handle signal is smaller than the elevation command from the elevation signal generator ESG, the relay is held in unless the control handle command becomes greater than the ESG command. This allows the gun to be elevated any time during the traverse of the obstacle.

During the traversal of the path between A and B, the gun follows different avoidance routes dictated by the output of the azimuth rate logic circuitry. Two different routes are represented in FIG. 1 by the broken lines, with a slower rate causing a path to be followed which more closely outlines the obstaclel During rapid azimuth traversal rates, the signal S at the output of the azimuth rate logic circuitry appears sooner, causing a more rapid onset of the elevation change signal.

To implement a reversal of the azimuth rotation while positioned near an object during a right azimuth control signal, the circuit of FIG. 16 is an example of apparatus satisfactory for implementing the method of the invention. The circuit of FIG. 17 is a similar circuit for reversing in proximity zones during an azimuth left signal. The purpose of the apparatus illustrated in FIGS. 16 and 17 is to reverse the azimuth when the gun is, positioned near a vertical obstacle. After reversal'of the gun and backing away from the obstacle, the

regular avoidance path appropriate to that particular rate signal is taken. It will be realized that the nature of the azimuth rate circuitry would allow a very close approach to the vertical boundaries of the obstacle under extremely slow azimuth rates. Or, similarly, a decrease in elevation without azimuth rotation could position the gun very close to a vertical outline of the obstacle.

In FIG. 16, a first input ofa three-inputAND circuit 94 is connected to the azimuth right output AR of the gun control. The second input of the AND circuit 94 is connected to contactor segment Pl on contactor C2. The third input of AND circuit 94 receives a signal when the elevation of the gun lies in segments E0 or E1 or E2. This is symbolized by an input at the AND circuit of (E0 E1 E2). The three-input AND circuit 96 has its three inputs connected to the azimuth right control line AR, contactor segment P2 on contactor C2, and contactor segment E3 on contactor C3. The outputs of the AND circuit 94 and 96 are connected to a two-input OR circuit 95. The output of the OR circuit 95 is connected to the base of an NPN transistor 97. The emitter of NPN transistor 97 is connected to a point of reference potential. A relay coil K6 is connected between a point of positive potential 98 and the collector of N PN transistor 97.

In the operation of the circuit of FIG. 16, when the azimuth position of the gun lies in proximity segments P1 or P2 with an azimuth right signal applied, and the elevation of the gun is such that a right rotation in azimuth would bring the gun against the obstacle, one of the AND circuits 94 or 96 will provide an output to turn on transistor 97, through OR circuit 95, which in turn actuates relay K6 causing the azimuth signal generator ASG in FIG. 6 to apply a negative signal to the azimuth left input line to the azimuth control circuit AC in FIG. 6 while simultaneously opening the control line azimuth right AR. This causes the gun to back away from the obstacle before beginning its normal avoidance path.

FIG. 17 is an analogous circuit for sensing the proximity zones during an azimuth left control signal. AND circuit 101 has three inputs which are connected to the azimuth left control line AL, the contactor segment P4 of contactor Cl, and both of the contractor segments E0 and E1 on contactor C3, through an OR circuit, for example. AND circuit 102 has its three inputs connected to the azimuth left control signal AL, contactor segment P3 of contactor C2, and both of the contactor segments E2 and E3 on contactor C3 through an OR circuit. The outputs of the AND circuits 101 and 102 are applied to the two inputs of an OR circuit 103 which has its output connected to the base of an NPN transistor 104. The emitter of NPN transistor 104 is connected to a point of reference potential. A relay K5 has its coil connected between a point of positive potential 105 and the collector of NPN transistor 104.

The operation of FIG. 17 is analogous with the operation of FIG. 16, with the segments connected to the inputs of the'AND circuits designed to actuate relay K5 whenever the gun is in one of the proximity zones to the right of an obstacle outline and an azimuth left signal is given. The relay K5 interrupts the normal azimuth left signal to the azimuth control circuitry AC in FIG. 6 and applies a positive signal to the azimuth right control circuitry from the azimuth signal generator ASG in FIG. 6 causing the gun to reversein direction until it leaves the proximity zone P3 or P4, whichever position the gun may be in.

A firing interlock making firing impossible while the gun is being deflected is also contemplated for use with the preferredembodiment. The method of the invention in altering the avoidance path dependent .on azimuth rate has the advantagethat optimal use can be made of the unobstructed firing range. Through the reversing procedures in the proximity zones, safe movement of the gun above the obstacle is guaranteed without mechanical braking of the drive even when the gun movement commands are given abruptly.

It will be realized that the contactors for indication of azimuth and elevation of the gun at any instance may be cams or other suitable switch mechanisms and are not limited to the use of rotary contactors as suggested in the preferred embodiment. Similarly, implementation of the method of the present invention through the apparatus described is a preferred embodiment although substitutions and variations will beobvious to those skilled in the art.

wherein I claim:

1. A method for automatically clearing a biaxially directionable gun from obstacles, said gun being slaved via a selsyn to a gunner operated sight, comprising:

monitoring the azimuth and elevation position and azimuth rate of said gun and the azimuth signal from said sight;

interrupting the elevation slaving channel from said sight to said gun when the monitored signals predict interference with an obstacle, said interruption being accelerated in response to an increased azimuth rate;

reversing the azimuth drive signal when said azimuth signal directs said gun toward an obstacle while said gun is in a predetermined region proximate said obstacle, causing said gun to back away from said obstacle before following an avoidance path; and

interposing an elevation drive signal to said gun to clear the obstacle.

2. Method of claim 1 wherein monitoring of said azimuth and elevation position comprises connecting a voltage source to one of a plurality of output leads corresponding to ranges of gun position.

3. Method of claim 1 including:

comparing the elevation drive signal to said gun with an elevation signal from said sight; and

holding the elevation drive signal interposed to clear the obstacle when said elevation signal from said sight is less than said elevation drive signal to said gun in the presence of an obstacle, to prevent oscillations of said gun.

4. Gun control apparatus for automatically clearing a biaxially directionable gun from obstacles, said gun being slaved via a selsyn to a gunner operated sight, comprising:

position sensing means for providing an output corresponding to predetermined regions of gun azimuth and elevation;

azimuth rate sensing means for providing an output dependent on the azimuth rate of said gun; azimuth reversing signal generator means connected to the azimuth drive of said gun;

proximity sensing means for actuating said azimuth reversing signal generator means when said gun is close to an obstacle and said sight signals azimuth rotation towards said obstacle; and

control means, connected to said position sensing means, said proximity sensing means, said azimuth rate sensing means and the azimuth output signal of said sight, for actuating the elevation drive of said gun to clear an obstacle, independent of the elevation signal from said sight, with the time of interposition dependent on azimuth rate and gun position.

5. Apparatus of claim 4 wherein said position sensing means comprises a multi-segment contactor, having a wiper arm driven by the gun drive and connected to a voltage source.

6. Apparatus of claim 4 wherein said azimuth rate sensing means comprises:

input means for connection to an azimuth rate-dependent signal level;

integrator means, connected to said input means,

having output means; and

threshold switch means, connected to said. output means of said integrator means, for signalling when the integrator output level exceeds a predetermined level. 7. Apparatus of claim 41 wherein said control means comprises:

switching means, having actuating means, for opening the elevation slaving channel between said sight and said gun and applying a predetermined voltage level to said elevation drive of said gun; and

logic circuit means, having input means connected to said position sensing means, to said azimuth rate sensing means, and to said azimuth output signal of said sight, for actuating said switching means at predetermined positions of azimuth and elevation of said gun, depending on azimuth rate and the sight azimuth output signal.

8. Apparatus of claim 6 wherein said integrator means includes a variable impedance input circuit for varying the integration time constant depending on the signal level at said input means.

9. Apparatus of claim 4 including:

comparator means for holding said control means to clear an obstacle when the elevation output signal of said sight differs by a predetermined amount from the elevation signal at said gun, said comparator means for preventing oscillations of said gun during actuation of said elevation drive. 

1. A method for automatically clearing a biaxially directionable gun from obstacles, said gun being slaved via a selsyn to a gunner operated sight, comprising: monitoring the azimuth and elevation position and azimuth rate of said gun and the azimuth signal from said sight; interrupting the elevation slaving channel from said sight to said gun when the monitored signals predict interference with an obstacle, said interruption being accelerated in response to an increased azimuth rate; reversing the azimuth drive Signal when said azimuth signal directs said gun toward an obstacle while said gun is in a predetermined region proximate said obstacle, causing said gun to back away from said obstacle before following an avoidance path; and interposing an elevation drive signal to said gun to clear the obstacle.
 2. Method of claim 1 wherein monitoring of said azimuth and elevation position comprises connecting a voltage source to one of a plurality of output leads corresponding to ranges of gun position.
 3. Method of claim 1 including: comparing the elevation drive signal to said gun with an elevation signal from said sight; and holding the elevation drive signal interposed to clear the obstacle when said elevation signal from said sight is less than said elevation drive signal to said gun in the presence of an obstacle, to prevent oscillations of said gun.
 4. Gun control apparatus for automatically clearing a biaxially directionable gun from obstacles, said gun being slaved via a selsyn to a gunner operated sight, comprising: position sensing means for providing an output corresponding to predetermined regions of gun azimuth and elevation; azimuth rate sensing means for providing an output dependent on the azimuth rate of said gun; azimuth reversing signal generator means connected to the azimuth drive of said gun; proximity sensing means for actuating said azimuth reversing signal generator means when said gun is close to an obstacle and said sight signals azimuth rotation towards said obstacle; and control means, connected to said position sensing means, said proximity sensing means, said azimuth rate sensing means and the azimuth output signal of said sight, for actuating the elevation drive of said gun to clear an obstacle, independent of the elevation signal from said sight, with the time of interposition dependent on azimuth rate and gun position.
 5. Apparatus of claim 4 wherein said position sensing means comprises a multi-segment contactor, having a wiper arm driven by the gun drive and connected to a voltage source.
 6. Apparatus of claim 4 wherein said azimuth rate sensing means comprises: input means for connection to an azimuth rate-dependent signal level; integrator means, connected to said input means, having output means; and threshold switch means, connected to said output means of said integrator means, for signalling when the integrator output level exceeds a predetermined level.
 7. Apparatus of claim 4 wherein said control means comprises: switching means, having actuating means, for opening the elevation slaving channel between said sight and said gun and applying a predetermined voltage level to said elevation drive of said gun; and logic circuit means, having input means connected to said position sensing means, to said azimuth rate sensing means, and to said azimuth output signal of said sight, for actuating said switching means at predetermined positions of azimuth and elevation of said gun, depending on azimuth rate and the sight azimuth output signal.
 8. Apparatus of claim 6 wherein said integrator means includes a variable impedance input circuit for varying the integration time constant depending on the signal level at said input means.
 9. Apparatus of claim 4 including: comparator means for holding said control means to clear an obstacle when the elevation output signal of said sight differs by a predetermined amount from the elevation signal at said gun, said comparator means for preventing oscillations of said gun during actuation of said elevation drive. 